The problem is that "Offensive pressure" isn't really a set per se. And beating shed involves a lot more than just having a mon that can kill it.
Anyway here's some form of counterplay:
Now I hear you, eject button does not actually kill shedinja. Nor does it really qualify as a set.
But being someone that usually runs moldysuit offensive mons, it can be incredibly annoying to actually get it in. If it's a ghost type you can get uturned on and pursuit trapped, if it's not you get slowly chipped by uturn. Shed teams are typically stall teams and have a lot of midground play, doubling to your moldysuit on the correct turn can prove to be extremely hard and may happen too late in the actual game for you to recover. It also means you have to play like a complete jackass for the beginning of the game which is always dodgy.
If you're battling a good Shedinja team, they won't usually endeavor straight away. In fact they probably won't endeavor until they've scouted your entire team, and will uturn around for most of the early game. This means eject button can often be slapped on anything that can switch on uturn.
Ho-Oh @ Eject Button
Ability: Magic Guard
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Bold Nature
- V-create
- Anchor Shot
- Recover
- Defog
Ho-oH is a pretty item agnostic mon for the most part.
That's all I have, honestly kinda hard to post something that isn't a core for this. Shed counterplay tends to be more of a team wide thing that a specific slot.